Deicing apparatus for jet engines



June 21, 1955 L, P. LEIGH, JR

DEICING APPARATUS FOR JET ENGINES 2 Sheets-Sheet l Filed NOV. l5, 1949 J rv E0/VAG@ l? .5E/GH, Je.

- JNVENTOR.

am Sab rroewex June 2l, 1955 L P, LEIGH, JR 2,711,453

DEICING APPARATUS FOR JET ENGINES Filed NOV. l5, 1949 2 Sheets-Sheet 2 .rllllllf Eo/Meo p. E/GH, Je.

I N V EN TOR.

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United States Patent O DEICING APPARATUS FOR JET ENGINES Leonard P. Leigh, Jr., Los Angeles, Calif.

Application November 15, 1949, Serial No. 127,408

2 Claims. (Cl. 20G-81.9)

My invention relates to deicing apparatus for jet engines and more particularly, although not necessarily, to deicing apparatus for the jet engines of aircraft. Such apparatus as heretofore proposed embodies a heater which is set into operation to deice the engine by electrical means under control of the pilot, and a device which indicates to the pilot icing conditions so that he may set the heater into operation to prevent icing of the engine. Such apparatus provide no means for automatically controlling the heater to effect deicing when required, and, hence, such control is left solely to the vigilance of the pilot. In consequence, many instances occur in which failure of the pilot to set the deicing apparatus into operation in time to prevent such accumulation of ice in the engine as to result in partial or complete destruction of the compressor thereof.

lt is a purpose of my invention to provide a deicing apparatus and a control means therefor which renders its operation entirely automatic to supply heated air to the engine to deice or prevent icing thereof when and as required. My apparatus may also include a manual control for the heater so that if for any reason the automatic control should fail, then the pilot may cause operation of the deicer. It is also a purpose of my invention to provide a deicing apparatus which utilizes the heat generated in the turbine itself as the heater of my apparatus, thus eliminating the necessity and expense of employing a separate source of heat.

A further purpose of my invention is to provide a deic ing apparatus which embodies one or more devices for controlling operation of the electrical switches thereof which, in turn, control operation of the heater, the device responding to air pressure to maintain the respective switch open, and to icing conditions occurring in the jet engine to cause closing of the switch and operation of the heater to prevent icing of the compressor, or to deice the same should it have inadvertently become iced. A still further purpose of my invention is the provision of a switch controlling device which includes a hollow body defining a non-linear passage, and a switch actuator movable bodily and upwardly therein in response to air under pressure entering the passage as the device is mounted on an aircraft in ight to maintain the switch open until the device becomes so iced as to prevent air entering the passage when the actuator falls and allows the switch to close. By reason of the non-linear form of the passage, air entering the same at relatively low velocities is caused to set up differential pressures on the actuator which causes it to rotate and thus prevent the air bearing moisture from accumulating and freezing on the actuator to cause it to stick in elevated or switch opening position and thus failing to drop and close the switch once the device becomes iced. Such relatively low air velocities exist when the aircraft is traveling at a speed under 400 miles per hour. Above this aircraft speed the velocity of air entering the passage rises to the extent of producing a pressure in the passage which raises its temperature sufficiently 2,7li,453 Patented June 21, 1955 to prevent moisture freezing on the actuator and sticking of the actuator in switch opening position.

I will describe only one form of deicing apparatus embodying my invention including two forms of switch control devices, and will then point out the novel features thereof in claims.

In the accompanying drawings:

Fig. l is a view showing in phantom an aircraft in elevation, a conventional type of jet engine applied to the aircraft, one form of deicing apparatus for the engine embodying my invention, and one form of control means for the apparatus also embodying my invention.

Fig. 2 is an enlarged vertical sectional View taken on the line 2 2 of Fig. l.

Fig. 3, is an enlarged vertical sectional view of the air heater of the apparatus.

Fig. 4 is a fragmentary sectional View of the heater inlet, and an elevational view of the device for circulating the valve in the inlet.

Fig. 5 is an enlarged front elevational View of one of the electrical switches of the control means for the deicing apparatus, and one form of control device for the switch.

Fig. 6 is a vertical sectional view taken on the line {5*6 of Fig. 5, showing the switch actuator in position to hold the switch open.

Fig. 7 is a view substantially similar to Fig. 6, showing an iced condition of the control device and the resultant positions of the actuator and switch.

Fig. 8 is a View similar to Fig. 7 showing another form of control device embodying my invention.

Having specific reference to the drawings, my invention is shown in Fig. l associated with a conventional aircraft A and a conventional jet engine E, with the rear end of both broken away. The engine comprises the usual air intake duct 15 which leads to the compressor 16, the latter in turn communicating with the combustion chamber 17 which leads to the turbine i8, and from the latter to the exhaust 19. For uniformly distributing air to the compressor a usual conical nose 2b is positioned in the duct 15 in advance of the compressor.

My deicing apparatus comprises an air heater H made up of a casing 21 having a lateral and tubular extension between its ends constituting an inlet 22 for hot gases from the turbine 18, such extension being connected to Aan outlet port 23 in the turbine housing.

For controlling the ow of hot gases from the turbine to the casing a valve 24, preferably of the buttery type, is provided, and it is fixed to a shaft 25 which projects from the extension where, by a set screw 26, it is coupled to the shaft 27 of a rotary solenoid 23 or other suitable form of electro-responsive device which when energized operates to rotate the valve to open position, and when deenergized moves the valve to closed position.

As shown in Fig. 3, the heater casing 21 is associated with an air conducting means which may be in the form of a pipe 29 that is secured in and extends through the casing where it is provided with ns 3G to accelerate the transfer of heat from the hot turbine gases to the pipe so that the air flowing through the latter will be heated to the degree required to produce effective deicing as will later be further explained.

To prevent the gases delivered to the casing 2i from accumulating therein to such a degree as to produce back pressure in the turbine, one or more outlet pipes 21a are connected to the casing and may lead to the leading edges of the wings of the aircraft to utilize the heat of such gases for deicing such edges.

Under forward movement of the aircraft air is caused to ow through the pipe 29 by extending its rear end upwardly and forwardly (see Fig. l) to provide a forwardly facing inlet 31. Likewise, as shown in Fig. l, the pipe 29 extends forwardly along the engine to a point adjacent the inlet end of the intake duct Where it is connected to a diffuser D located in the duct and comprising tubes 32 fixed in and radiating from the center of the duct. These tubes have a cross sectional contour of stream line form, and their rear sides are formed with outlets 33 through which the hot air delivered thereto from the pipe 29 is discharged rearwardly into the intake duct.

One or more devices K are embodied in the apparatus to control one or more electrical switches S for energizing the solenoid 28 from a source of current to openV the valve 24. in the present instance I have shown in Fig. l two control devices K, one located in the intake duct 15 immediately to the rear of the diffuser D, and the other medially of the ends of the duct.

These devices K are identical in construction and, as shown in Figs. 5 and 6, each comprises a tubular member or pipe 34 of L-form which is preferably arranged in a vertical plane with the horizontal leg thereof positioned in the duct 15, and its vertical leg secured to and extending upwardly through the top of the duct by riveting a ange 35 on the pipe to the duct wall. Screwthreaded on the upper end of the vertical pipe leg is a cage 36 for an actuator 37 which may be in the form of a metal ball of a diameter to normally seat on the upper end of the pipe as in Fig. 7, but when elevated to engage the edge of a port 3S in the cage to partly close the port.

The forward end of the horizontal leg of the pipe 34 is provided with a cap 39 which is perforated to form a screen 40 through which air under pressure is caused to flow into the pipe under forward movement of the aircraft, and lift the ball to the elevated position in Fig. 6.

Each switch S is normally urged to closed position as shown in Fig. l, and may be contained in a sleeve 41 of insulating material suspended directly above the port 38 from a support 42. An operating element for opening the switch S under elevating movement of the ball 37 is provided, and such element may be in the form of a rod 43 slidable in the sleeve 41 and normally extending into the port 38 so as to be engaged and lifted by the ball thus causing it to be moved upwardly to open the switch as in Fig. 6.

In Fig. 8 the switch S is shown positioned horizontally and the sleeve 41 and the rod 43 likewise, with the rod extending through the side of the cap 39 to be engaged by the ball 37 when in lowered position to maintain the switch open. Thus when the ball is elevated by the pressure of air entering the pipe through the screen 40 the rod will be disengaged to allow the switch to close.

The perforations forming the screen 40 constitute a plurality of air inlet ports each of which is of such size that it can be closed by ice forming on the surface of the screen. `When all of the ports are closed by ice formation, or a portion thereof suflicient to restrict air flow into the pipe such as to reduce the pressure thereof to a point which is insufficient to maintain the ball 37 elevated, then the ball gravitates to lowered position allowing the switch to open. In the operation of either control device K, when the velocity of the air flow, into the pipe 34 is relatively low such as when the aircraft is traveling at speeds less than 400 miles per hour, -the ball 37 in its elevated position is constantly rotated by the air. Under such rotation the entrained moisture in the air as deposited on the ball is blown therefrom by the air and outwardly of the opening 38, it being understood that at no time has the ball an airtight seat in the opening, thus permitting air seepage from the opening at all times.

Thus moisture is prevented at all times from accumulating on the ball which, if permitted, would freeze the ball to the cap 36 and hold the switch S in open position after the screen 40 was closed by ice formation, thus rendering the device inoperative for the purpose.

Rotation of the ball 37 results from the angular form of the pipe 34, since the pressure of air flowing there through as imposed on the ball is less on the right side thereof than on the left, thus causing the ball to rotate in a clockwise direction. This differential air pressure results from the fact that theV resistance offered to the flow of air by the inner surface of the vertical leg of the pipe is greater at the right side than at the left side thereof, and, hence the prevailing air pressure as imposed on the ball is at the left side thereof.

When the velocity of air ow into the pipe 34 is relativelyhigh such as when the aircraft is traveling at speeds above 400 miles per hour, the air beneath the ball is compressed since its escape from the opening 3S is restricted by the ball. Under such air pressure the ball may cease to rotate, but such ice formation on the ball as to freeze it to the cap is nevertheless prevented because the air pressure raises the temperature of the air to a degree suicient to prevent the moisture deposited on the ball from turning into ice.

Thus from the aforedescribed action of the air on the ball 37 either at low or high velocity the ball is assured of gravitating to a lowered position once air flow into the pipe 34 ceases or diminishes because of ice formation on the screen 40, thereby allowing the switch S to close as intended.

Shown diagrammatically in Fig. l is a main circuit and a branch circuit both controlled by a manually operable switch including an arm 44 movable to engage a contact 4S for the main circuit, and to engage a contact 46 .for closing the branch circuit. Included in both circuits is the solenoid 28, and source of current such as the battery 47 while the two switches S are included only in the main circuit and connected in parallel therein. Also in the main circuit ahead of the switches is an electric lamp 48 which functions as a signal to indicate to the pilot when the deicing apparatus is in operation through closure of either of the switches S. One side of the battery 47 and one side of the solenoid 2S are grounded through the body of the aircraft.

When the aircraft is in flight my apparatus with the switch arm 44 engaging the contact 45, will operate automatically as follows:

Air is continuously forced into pipe inlet 31 and thence through the pipe 29 to be emitted from the diffuser D into the engine intakeduct 15. If the air entering the duct from its forward end is of such temperature as not toform ice on the inner wall of the duct or on the nose 20, then no ice will form on the caps 39 of the control` devices K and, hence, the ports of the screen 4t) remain open to allow free flow of air into the pipes 34 at such pressure as to maintain the balls 37 elevated and the switches S open. Thus the solenoid 28 remains deenergized and the valve 24 closed to prevent the hot gases from the turbine 18 entering the casing 21 and heating the air traversingthe pipe 29. Accordingly, the heater H is ineffective to supply heated air to the diffuser D under temperatures existing in the duct 16 and incapable of forming ice therein.

However, if the temperature of the air entering the duct 15 is such as to form ice therein, icing of either or both of the caps 39 will occur, see Figs. 7 and 8, to close theV screen ports and thus discontinue the ow of air into the pipe 34 so that the ball 37 drops to allow the switch S to close. Upon closure of either switch the main circuit for the solenoid 28 isclosed to energize the latter and open the valve 24, thus setting the heater H into operation to heat the air traversing the pipe 29. This main circuit may be traced as follows: From one side of battery 47, wire 49, switch arm 44, contact 45, wire 50, signal 48, wires 51 and 52 to either switch S, wire 5,3 or 54 to -wire 55 and then to one side of solenoid 28. From the grounded side of the solenoid current returns to the grounded side of the battery 47.

The heated air as now emitted from the diffuser D functions to so increase the temperature of the air traversing the duct 1S as to melt whatever ice may have formed therein, and particularly on the nose 2i) where it usually so rapidly forms as to break oil and be carried by the blast of air into the compressor to damage the latter. Coincident with this ice melting operation the heated air also melts the ice accumulated on either or both of the caps 39. Once this occurs air is again admitted to the pipe or pipes 34 to lift the ball 37 and open the switch S through the rod 43 to disrupt the main circuit and thereby deenergize the solenoid causing closing of the heater valve to discontinue further heating of the air emitted from the diffuser.

Manifestly, either control device K is operable automatically by the temperature of the air traversing the duct to supply heated air thereto to deice the engine before the ice becomes a damaging factor to the cornpressor or other parts of the engine.

Manual control of operation of the heater to supply heated air to the duct 1S is achieved by closure of the branch circuit through movement of the switch arm 44 to engage the contact 46 to supply current from the battery 47 through wires 57 and S5 to the solenoid 28 thereby energizing the latter and opening the valve 24.

Although I have herein shown and described only one form of deicing apparatus and one form of control means therefor, each embodying my invention, it is to be understood that various changes and modications may be made therein without departing from the spirit of my invention and the spirit and scope of the appended claims,

What I claim is:

1. A device for controlling operation of a switch including a tubular casing open at one end and a rod slidable longitudinally in the casing and at one end protruding from the open end or the casing; said device cornprising a tubular L-shaped body of an even diameter throughout its length and having a vertical arm and a horizontal arm, the lower end of the vertical arm and the inner end of the horizontal arm merging into each other, a cap 'for the outer end of the horizontal arm having perforations constituting air inlets, a cage of inverted cupshape into which the protruding end of said rods eX- tends screwed upon the upper end of the vertical arm and projecting upwardly therefrom and at its top being formed with a central opening axially aligned with the vertical arm and constituting an air outlet and a ball loose in said cage and being of greater diameter than the tubular casing and the opening in the top of the cage, said ball being normally in a lowered position at rest upon the upper end of the vertical arm and being shiftable upwardly by action of air passing inwardly through the horizontal arm and outwardly through the vertical arm to a raised position in which it rotates in blocking rotation to the opening in the top of the cage and forces the rod longitudinally into the casing of the switch.

2. A device for controlling operation of an electrical switch having a vertically disposed operating rod normally disposed in a lowered position and shiftable upwardly to an adjusted position, said device comprising a hollow tubular body of an even diameter throughout its length and having a vertical arm and a horizontal arm communi ting at its inner end with the lower end of the vertical a through an upwardly curved arcuate portieri, a at the outer end of the horizontal arm formed with pertorations and constituting a screen for incoming air, a cage screwed upon and extending upvvardiy from the upper end of the vertical arm and formed at its top with a central opening through which the lower portion or the rod extends into the cage, and a rod-engaging ball loose in said cage and being of greater diameter than the tubular body and the opening in the top of the cage, said ball when in a lowered position being seated upon the open upper end of the vertical arm, and said ball being shiftable upwardly oy air flowing through the vertical arm to a raised position in which it supports the rod in a raised position and is rotated against edges of the opening to remove ice from the ball.

References Cited in the file of this patent FOREIGN PATENTS 157,550 Great Britain Jan. 17, 1921 

